The present invention relates to a tool for cleaning or repairing the screw threads on studs, bolts, and similar threaded members.
Such tools generally comprise a device having internal thread-cutting dies or teeth in which the stud or bolt is clamped. The tool is then backed off or unscrewed to reset the threads.
In U.S. Pat. No. 2,700,166 of McKenzie, for example, a rethreading tool comprising a cup shaped holder containing opposed jaw members is shown. The jaw members have opposed semi-circular thread cutting teeth. The jaws are spread apart to receive a member to be rethreaded by a cam mechanism.
U.S. Pat. No. 3,956,787 of Crumpacker describes a thread reconditioning tool comprising a hollow tube slidably receiving a collet chuck which is connected to a handle for moving the chuck between an extended and retracted position. The chuck has internal thread cutting teeth on separate jaws which are contracted together to grip a stud or bolt on retraction into the tube by means of inclined cam surfaces on the jaws.